Katipo spider

Latrodectus katipo

What do they look like?

The adult female of katipo is a small spider with a pea-sized abdomen. It is black and may sometimes have white markings both at the front of the abdomen and also bordering a pronounced red stripe. This stripe starts in the middle of the abdomen and runs towards the rear end of the spider. There is also a a red hourglass shape on the underside of the abdomen. In the northern half of the North Island, a black form of katipo exists. It lacks the red stripe but is otherwise similar in size and appearance. This black form was previously known as Latrodectus atritus but both the red stripe and black forms are now regarded as the same species.

Males and juveniles of both forms have a lot of white that gives way to black as the spiders moult. Males go through fewer moults than females and they never attain the females' size or dark colour. Indeed, they still look very much like juveniles despite being fully grown.

Where are they found?

In amongst grasses, sedges, driftwood, and flotsam on sandy beaches throughout New Zealand. The black form of katipo appears to be confined to the northern half of the North Island, while the red-striped form can be found south of there, reaching its southern limit on the Otago coast. On the South Island's West Coast it occurs from Greymouth north.

In some parts of the country, the katipo appear to have been replaced by a look-alike species, the black cobweb spider (Steatoda capensis), possibly due to habitat alteration by humans.

The introduction of sand-binding plants such as marram grass, lupins, and others, along with the reclamation of dune systems for agriculture and forestry, deprive katipo of the conditions they need to prosper.

Due to a steady population decline, katipo is now classified as Absolutely Protected under the Wildlife Act.

What are their habits?

Katipo spiders make webs at the base of beach grasses and other vegetation, but are also known to make their homes amongst driftwood and debris. They typically catch ground-crawling insects such as beetles. Egg sacs are produced towards the end of the year and are guarded by the female in her lair.

How bad is the bite?

Even though bites are rare, it is not without reason that these spiders have earned the name katipo, a Māori name that translates as 'night-stinger'.

These spiders belong to the worldwide genus Latrodectus, more commonly known as the widow spiders. Members of this group include the Australian redback (Latrodectus hasselti) and the black widow (L. mactans) of North America.

All members of this genus share a similar reputation for inflicting unpleasant and sometimes fatal bites on humans. It is worth noting that only the female is capable of biting a person, as the male's fangs are too small.

Katipo bites are very uncommon, and while likely to be unpleasant, are not likely to prove lethal. The very few fatal cases reported are based on rather dubious records from the 1800s.

Typical symptoms include pain at the site of the bite, which may spread to other areas, becoming more intense over the hours that follow. Sweating, malaise, fever, shaking, and many other symptoms may occur, but abdominal cramping is particularly common. An icepack may relieve pain and delay the onset of further symptoms. An antivenom is available at hospitals.